ALD of metal-containing films using cyclopentadienly compounds

ABSTRACT

Atomic layer deposition (ALD) type processes for producing metal containing thin films comprise feeding into a reaction space vapor phase pulses of metal containing cyclopentadienyl precursors as a metal source material. In preferred embodiments the metal containing cyclopentadienyl reactant comprises a metal atom that is not directly bonded to an oxygen or halide atom. In other embodiments the metal atom is bonded to a cyclopentadienyl compound and separately bonded to at least one ligand via a nitrogen atom. In still other embodiments the metal containing cyclopentadienyl compound comprises a nitrogen-bridged ligand.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/602,514, filed on May 23, 2017, which is a continuation of U.S.application Ser. No. 15/363,998, filed Nov. 29, 2016 and issued as U.S.Pat. No. 9,670,582, which is a continuation of U.S. application Ser. No.15/006,532, filed Jan. 26, 2016 and issued as U.S. Pat. No. 9,677,175,which is a continuation of U.S. application Ser. No. 14/311,154, filedJun. 20, 2014 and issued as U.S. Pat. No. 9,273,391, which is acontinuation of U.S. application Ser. No. 11/588,595 filed Oct. 27, 2006and issued as U.S. Pat. No. 8,795,771, each of which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This application relates generally to processes for depositing metalcontaining films. Certain embodiments relate to processes formanufacturing metal containing thin films by atomic layer depositionusing volatile metal containing cyclopentadienyl compounds as sourcematerials.

Description of the Related Art and Summary of the Invention

Atomic layer deposition (“ALD”) refers to vapor deposition-type methodsin which a material, typically a thin film, is deposited on a substratefrom vapor phase reactants. It is based on sequential self-saturatingsurface reactions. ALD is described in detail, for example, in U.S. Pat.Nos. 4,058,430 and 5,711,811, incorporated herein by reference.

According to the principles of ALD, the reactants (also referred to as“source chemicals” or “precursors”) are separated from each other,typically by inert gas, to prevent gas-phase reactions and to enable theself-saturating surface reactions. Typically, one of the precursorsself-limitingly adsorbs largely intact, without thermal decomposition,while one of the precursors strips or replaces the ligands of theadsorbed layer. Surplus source chemicals and reaction by-products, ifany, are removed from the reaction chamber by purging with an inert gasand/or evacuating the chamber before the next reactive chemical pulse isintroduced. ALD provides controlled film growth as well as outstandingconformality. Various ALD recipes are possible with different reactantssupplied in sequential pulses each with different functions, but thehallmark of ALD is self-limiting deposition.

Metal containing cyclopentadienyl compounds are technologically veryimportant and have a variety of industrially useful properties. One suchproperty is the ability for these compounds to adhere to both metals andnonmetals. Furthermore, without being bound to any theory, it isbelieved that the attached cyclopentadienyl ligand(s) contribute tooverall compound stability. As a result, metal containing compounds canbe used, for example, as precursors for forming adhesion layers invarious structures including semiconductors, insulators, andferroelectrics.

Metal containing films have previously been manufactured by physicalvapor deposition (PVD) methods. These processes are well-known in theart. However, the PVD process has a number of drawbacks. For example,the PVD process is difficult or impossible to use for depositing thinfilm layers on complicated surfaces such as microelectronic surfaceswith deep trenches and holes. In contrast, ALD processes can providefilms of uniform quality and thickness.

Several different metal containing precursors have been previously usedin ALD methods, but these precursors have a tendency to incorporateimpurities into the growing thin film. For example, known processesutilizing metal chlorides, such as TiCl₄, and hydrogen plasmaincorporate halide impurities into the resulting thin films. Similarconcerns arise for known non-halide metal precursors such as metalcontaining alkoxides, like Ti(OMe)₄, where oxygen tends to remain in thefilm as an impurity.

As an alternative to the halide and oxide precursors, metal alkylamides,have been used in the art as precursors for ALD processes. However,these compounds suffer from thermal instability such that it can bedifficult to find a deposition temperature that will not causedecomposition of the precursors and will keep the thin film atomsintact, but will still keep the precursors in vapor phase and providethe activation energy for the surface reactions.

In one aspect of the invention, atomic layer deposition (ALD) processesfor producing metal containing thin films are provided. The processespreferably comprise alternately contacting a substrate in a reactionspace with vapor phase pulses of at least one metal containingcyclopentadienyl precursor and at least one second reactant, such that athin metal-containing film is formed on the substrate. In someembodiments, the metal containing cyclopentadienyl precursor comprises ametal atom that is not directly bonded to a halide or oxygen atom. Infurther embodiments, the metal atom is bonded to at least onecyclopentadienyl ligand and separately bonded to at least one ligand vianitrogen, wherein the ligands may comprise oxygenated or halogenatedgroups not directly bonded to the metal. In other embodiments thecyclopentadienyl precursor does not contain halide or oxygen atoms atall. In yet other embodiments, the metal containing cyclopentadienylprecursor comprises a nitrogen-bridged ligand.

In preferred embodiments, the metal containing cyclopentadienylprecursor comprises a metal selected from the group consisting of Al,Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Tc, Ru, Rh, La,Hf, Ta, W, Re, Os, and Jr, more preferably from the group consisting ofTi, Zr, Hf, Ta, W, Nb, and Mo. In some embodiments, the metal containingcyclopentadienyl precursor comprises a metal with a trivalent oxidationstate.

In another aspect of the invention, ALD processes for forming anelemental metal thin film are provided. The processes preferablycomprise alternately contacting a substrate with a metal containingcyclopentadienyl precursor as described above and a second reactant suchthat an elemental metal thin film is formed on the substrate. In someembodiments, the second reactant is selected from hydrogen or hydrogenplasma. The cycles are repeated until a thin film of the desiredthickness has been deposited.

In another aspect of the invention, ALD processes for forming a metalnitride thin film are provided. The processes preferably comprisealternately contacting a substrate with a metal containingcyclopentadienyl reactant as provided above and a second nitrogencontaining reactant such that a metal nitride thin film is formed on thesubstrate. In some embodiments, the second reactant is selected fromNH₃, N₂ plasma, N₂/H₂ plasma, hydrazine, and/or hydrazine derivatives.

In another aspect of the invention, an atomic layer deposition processfor forming a metal carbide thin film comprises alternately contacting asubstrate with a metal containing cyclopentadienyl precursor as providedabove and second carbon containing reactant such that a metal carbidethin film is formed on the substrate. In some embodiments, the carbonsource is a hydrocarbon such as an alkane, alkene, and/or alkyne. Inother embodiments, the carbon containing compound preferably comprises acentral atom selected from group B, Al, Ga, In, Si, Ge, Sn, P, As, or S.

In another aspect, multicomponent thin films are deposited by atomiclayer deposition processes. The processes preferably comprise at leasttwo growth sub-cycles with the first sub-cycle comprising contacting asubstrate with alternate and sequential vapor phase pulses of a firstmetal precursor and a first reactant, and then a second sub-cyclecomprising contacting the substrate with alternate and sequential vaporphase pulses of a second metal precursor and a second reactant. In someembodiments the second metal precursor is different from the first metalprecursor. For example, the second metal precursor may comprise adifferent metal from the first metal precursor. In other embodiments thesecond reactant is different from the first reactant. For example, thefirst and second reactants may contribute different species, such as N,C, or O to the growing film. In at least one of the growth sub-cyclesthe metal precursor is a metal containing cyclopentadienyl precursor asdescribed above. The sub-cycles may be repeated in equivalent numbers.However, in some embodiments the ratio of the sub-cycles is varied toachieve the desired film composition, as will be apparent to the skilledartisan.

In another aspect, a multicomponent thin film comprises at least oneelemental metal layer whereby at least one of the growth sub-cyclescomprises contacting a substrate with alternate and sequential vaporphase pulses of a metal containing cyclopentadienyl precursor and areactant. In some embodiments, the reactant is selected from hydrogenand hydrogen plasma.

In another aspect, a multicomponent thin film comprising at least onemetal nitride layer is deposited by atomic layer deposition typeprocesses. The processes preferably comprise at least one sub-cycle ofalternating and sequential pulses of a metal containing cyclopentadienylprecursor and a nitrogen containing reactant. In some embodiments thenitrogen containing material is selected from the group consisting ofNH₃, N₂ plasma, N₂/H₂ plasma, hydrazine, and hydrazine derivatives.

In another aspect, a multicomponent thin film comprising at least onemetal carbide layer is deposited by atomic layer deposition typeprocesses. The processes preferably comprise at least one sub-cycle ofalternating and sequential pulses of a metal containing cyclopentadienylprecursor and a carbon source material. In some embodiments the carbonsource material is a hydrocarbon. In other embodiments, the hydrocarbonis selected from alkanes, alkenes, and alkynes. The carbon containingcompound may be one with a central atom selected from group B, Al, Ga,In, Si, Ge, Sn, P, As, or S.

The disclosed ALD processes preferably comprise at least one sub-cyclecomprising alternating and sequential pulses of a metal containingcyclopentadienyl precursor. Preferably, the metal containingcyclopentadienyl precursor comprises at least one cyclopentadienylligand and a metal that is not directly bonded to a halide or oxygenatom. Alternatively, the metal precursor comprises at least onecyclopentadienyl ligand and at least one ligand that is separatelybonded to the metal via nitrogen, wherein each ligand may containoxygenated or halogenated groups not directly bonded to the metal. Insome preferable embodiments, at least one chelating ligand, such as abidentate ligand, is bonded to the metal via nitrogen. Additionally, themetal containing cyclopentadienyl precursor may comprise anitrogen-bridged ligand. In some embodiments the precursor does notcomprise any oxygen or halide atoms.

Preferably, the metal precursor is selected from (R¹R²R³R⁴R⁵Cp)_(x)-MR⁰_(z)—(R⁶)_(y), R¹R²R³R⁴R⁵Cp)_(x)-MR⁰ _(z)—(NR¹R²)_(y),(R¹R²R³R⁴R⁵Cp)_(x)-MR⁰ _(z)—(NR¹NR²R)_(y), and (R¹R²R³R⁴R⁵Cp)_(x)-MR⁰_(z)—[(NR¹NR²)CNR³]_(y), (R¹R²R³R⁴R⁵Cp)_(x)-MR⁰_(z)—[(NR¹NR²)CNR³R⁴]_(y). The metal containing cyclopentadienylprecursor may be, for example, a titanium cyclopentadienyl compoundhaving the formulas described. In some embodiments the precursor isbiscyclopentadienyl triisopropylguanidinato titanium (III).

Preferably the substrate temperature is higher than the evaporationtemperature of the precursor and lower than the decompositiontemperature of the precursor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing a typical process flow according to somepreferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Stable metal containing precursors that have thermal stability yet avoidpossible contamination problems are desirable for ALD processes. Asdiscussed below, metal cyclopentadienyl compounds with the particularcharacteristics described herein have been found to be good metalprecursors for depositing metal containing thin films by ALD becausethese compounds avoid many of the problems associated with the use ofpreviously known metal precursors.

In context of the present invention, “an ALD type process” generallyrefers to a process for depositing thin films on a substrate molecularlayer by molecular layer. This controlled deposition is made possible byself-saturating chemical reactions on the substrate surface. Vapor phasereactants are conducted alternately and sequentially into a reactionchamber and contacted with a substrate located in the chamber to providea surface reaction. Typically, a pulse of a first reactant is providedto the reaction chamber where it chemisorbs on the substrate surface ina self-limiting manner. Any excess first reactant (and reactantbyproducts, if any) is then removed and a pulse of a second reactant isprovided to the reaction chamber. The second reactant reacts with theadsorbed first reactant, also in a self-limiting manner. Excess secondreactant and reaction by-products, if any, are removed from the reactionchamber. Additional reactants may be supplied in each ALD cycle,depending on the composition of the thin film being deposited. Thiscycle is repeated to form a metal containing thin film of desiredthickness.

The pressure and the temperature of the reaction chamber are adjusted toa range where physisorption (i.e., condensation of gases) and thermaldecomposition of the precursors are avoided. Consequently, only up toone monolayer (i.e., an atomic layer or a molecular layer) of materialis deposited at a time during each pulsing cycle. The actual growth rateof the thin film, which is typically presented as A/pulsing cycle,depends, for example, on the number of available reactive surface siteson the surface and bulkiness of the reactant molecules.

Gas phase reactions between precursors and any undesired reactions withreaction by-products, if any, are preferably inhibited or prevented tomaintain self-limiting behavior and minimize contamination. Reactantpulses are separated from each other and the reaction chamber is purgedwith the aid of an inactive gas (e.g. nitrogen or argon) and/orevacuated between reactant pulses to remove surplus gaseous reactantsand reaction by-products from the chamber. The principles of ALD typeprocesses are discussed e.g. in the Handbook of Crystal Growth 3, ThinFilms and Epitaxy, Part B: Growth Mechanisms and Dynamics, Chapter 14,Atomic Layer Epitaxy, pp. 601-663, Elsevier Science B.V. 1994, thedisclosure of which is incorporated herein by reference.

An extensive description of ALD precursors and ALD-grown materials canbe found in the Handbook of Thin Film Materials, Vol. 1: Deposition andProcessing of Thin Films, Chapter 2 “Atomic Layer Deposition”, pp.103-159, Academic Press 2002, incorporated by reference herein.

In the context of the present application “a reaction space” designatesgenerally a reaction chamber, or a defined volume therein, in which theconditions can be adjusted so that deposition of a thin film ispossible.

In the context of the present application, “an ALD type reactor” is areactor where the reaction space is in fluid communication with aninactive gas source and at least one, preferably at least two precursorsources such that the precursors can be pulsed into the reaction space.The reaction space is also preferably in fluid communication with avacuum generator (e.g. a vacuum pump), and the temperature and pressureof the reaction space and the flow rates of gases can be adjusted to arange that makes it possible to grow thin films by ALD type processes.The reactor also includes the mechanism, such as valves and programming,to pulse and maintain separation between the reactants.

As is well known in the art, there are a number of variations of thebasic ALD method, including PEALD (plasma enhanced ALD) in which plasmais used for activating reactants. Conventional ALD or thermal ALD refersto an ALD method where plasma is not used but where the substratetemperature is high enough for overcoming the energy barrier (activationenergy) during collisions between the chemisorbed species on the surfaceand reactant molecules in the gas phase so that up to a molecular layerof thin film grows on the substrate surface during each ALD pulsingsequence or cycle. As used herein, the term “ALD” covers both PEALD andthermal ALD.

“Metal source material” and “metal precursor” are used interchangeablyto designate a volatile or gaseous metal compound that can be used in anALD process and contributes metal to a deposited film.

The term “multicomponent thin film” covers thin films comprising atleast two different metal atoms.

According to preferred embodiments, metal containing thin films aredeposited by ALD using metal containing cyclopentadienyl precursors. Insome embodiments, the metal containing cyclopentadienyl precursorcomprises a metal selected from the group consisting of Ti, Zr, Hf, Ta,W, Nb, and Mo. In other embodiments, the metal has a trivalent oxidationstate. In further embodiments, the trivalent metal is selected from thegroup consisting of Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os, and Ir.

Preferably, the metal containing cyclopentadienyl (Cp) precursorcomprises at least one cyclopentadienyl ligand and does not containhalide or oxygen atoms. However, in other embodiments the metalprecursor may contain halide or oxygen atoms not directly bonded to themetal. In still other embodiments the precursor contains at least onecyclopentadienyl ligand and at least one ligand that is bonded to themetal via nitrogen, wherein each ligand may contain oxygen or halogengroups not directly bonded to the metal. In some embodiments, theprecursor may contain nitrogen-bridged ligands. Exemplary recursors canbe selected from the group consisting of compounds according to FormulaeI-VII as described below.

The general formula for a metal precursor comprising at least onecyclopentadienyl ligand can be written according to Formula I:(R¹R²R³R⁴R⁵Cp)_(x)-MR⁰ _(z)—(R⁶)_(y)  (I)

-   -   wherein M is a metal preferably selected from the group        consisting of Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,        Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os, and Ir;    -   wherein each R¹, R², R³, R⁴, R⁵, and R⁰ is independently        selected from:        -   i. hydrogen;        -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl            groups, which are independently substituted or            unsubstituted;        -   iii. carbocyclic groups, such as aryl, preferably phenyl,            cyclopentadienyl, alkylaryl, and halogenated carbocyclic            groups; and        -   iv. heterocyclic groups;    -   wherein R⁶ is independently selected from:        -   i. hydrogen;        -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl            groups, which are independently substituted or            unsubstituted;        -   iii. carbocyclic groups, such as aryl, preferably phenyl,            cyclopentadienyl, alkylaryl, and halogenated carbocyclic            groups;        -   iv. heterocyclic groups; and        -   v. NR¹R²; and    -   wherein both x and y are ≧1 and z≧0.

In some embodiments, the metal containing cyclopentadienyl compoundcomprises at least one ligand that is bonded to the metal via nitrogenas depicted by Formula II:(R¹R²R³R⁴R⁵Cp)_(x)-MR⁰ _(z)—(NR¹R²)_(y)  (II)

-   -   wherein M is a metal preferably selected from the group        consisting of Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,        Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os, and Ir;    -   wherein each R¹, R², R³, R⁴, R⁵, and R⁰ is independently        selected from:        -   i. hydrogen;        -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl            groups, which are independently substituted or            unsubstituted;        -   iii. carbocyclic groups, such as aryl, preferably phenyl,            cyclopentadienyl, alkylaryl, and halogenated carbocyclic            groups; and        -   iv. heterocyclic groups; and    -   wherein both x and y are ≧1 and z≧0.

In Formula II, the alkyl, alkenyl and alkynyl groups can be selectedfrom any linear or branched alkyl, alkenyl and alkynyl groups which have1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, in particular 1to 6 carbon atoms. Examples of such alkyl groups include methyl; ethyl;n- and i-propyl-; n-, i- and t-butyl-; n- and isoamyl; n- and isopentyl;n- and isohexyl; and 2,3-dimethyl-2-butyl. In some embodiments, alkylgroups are preferred. In other embodiments, the C₁₋₂₀, preferably C₁₋₁₀,in particular C₁₋₆, alkenyl and alkynyl groups include the correspondinggroups having a corresponding degree of unsaturation.

Preferably, the metal containing cyclopentadienyl precursor is acompound having at least one cyclopentadienyl ligand and at least onechelating ligand, for example, a bidentate ligand. In some embodiments,this compound is depicted by Formula III, (R¹R²R³R⁴R⁵Cp)_(x)-MR⁰_(z)—(NR¹NR²R)_(y), as follows:

-   -   wherein M is a metal preferably selected from the group        consisting of Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,        Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os, and Ir;    -   wherein R can be any linear and branched C₁-C₂₀ alkyl, alkenyl        and alkynyl groups, which are independently substituted or        unsubstituted and R can be bonded to two bridging nitrogen atoms        any point of alkyl, alkenyl and alkynyl groups;    -   wherein each R¹, R², R³, R⁴, R⁵, and R⁰ is independently        selected from:        -   i. hydrogen;        -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl            groups, which are independently substituted or            unsubstituted;        -   iii. carbocyclic groups, such as aryl, preferably phenyl,            cyclopentadienyl, alkylaryl, and halogenated carbocyclic            groups; and        -   iv. heterocyclic groups; and    -   wherein both x and y are ≧1 and z≧0.

In other preferable embodiments, the metal containing cylcopentadienylprecursor is depicted by Formula IV, (R¹R²R³R⁴R⁵Cp)_(x)-MR⁰_(z)—[(NR¹NR²)CNR³]_(y), as follows:

-   -   wherein M is a metal, preferably selected from the group        consisting of Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,        Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os, and Ir; wherein each        R¹, R², R³, R⁴, R⁵, and R⁰ is independently selected from        -   i. hydrogen;        -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl            groups, which are independently substituted or            unsubstituted;        -   iii. carbocyclic groups, such as aryl, preferably phenyl,            cyclopentadienyl, alkylaryl, and halogenated carbocyclic            groups; and        -   iv. heterocyclic groups; and    -   wherein both x and y are ≧1 and z≧0.

In further preferable embodiments, the metal containing cyclopentadienylprecursor is depicted by Formula V, (R¹R²R³R⁴R⁵Cp)_(x)-MR⁰_(z)—[(NR¹NR²)CNR³R⁴]_(y), as follows:

(V) Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Tc, Ru,Rh, La, Hf, Ta, W, Re, Os, and Ir

-   -   wherein M is a metal, preferably selected from the group        consisting of Al, Ga, In, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,        Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os, and Ir; wherein each        R¹, R², R³, R⁴, R⁵, and R⁰ is independently selected from:        -   i. hydrogen;        -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl            groups, which are independently substituted or            unsubstituted;        -   iii. carbocyclic groups, such as aryl, preferably phenyl,            cyclopentadienyl, alkylaryl, and halogenated carbocyclic            groups; and        -   iv. heterocyclic groups; and    -   wherein both x and y are ≧1 and z≧0.

In a particular example, the metal containing cyclopentadienyl precursoris biscyclopentadienyl triisopropylguanidinato titanium (III) asdepicted by Formula VI:

In further embodiments, the metal containing cyclopentadienyl compoundas described in Formulae I-VI may comprise R⁰, R¹, R², R³, R⁴, R⁵, andR⁶ wherein each is independently selected from

-   -   i. hydrogen;    -   ii. linear and branched C₁-C₂₀ alkyl, alkenyl and alkynyl        groups, which are independently substituted or unsubstituted;    -   iii. carbocyclic groups, such as aryl, preferably phenyl,        cyclopentadienyl, and alkylaryl; and    -   iv. heterocyclic groups

Optionally, a metal containing cyclopentadienyl compound as describedmay comprise modified cyclopentadienyl groups. In some embodiments, themodified cyclopentadienyl groups are selected from the group consistingof Me₅Cp, MeCp, EtCp, and Me₃SiCp. In further embodiments, the metalcontaining cyclopentadienyl compound may comprise an anionic ordianionic guanidinate ligand such as a triisopropylguandinate ligand.

As illustrated in the FIGURE, in a preferred ALD type process, a gasphase pulse of first reactant, a metal containing cyclopentadienylcompound (100) is introduced into the reaction space of an ALD reactor,where it is contacted with a suitable substrate. No more than amonolayer of the metal precursor adsorbs on the substrate surface in aself-limiting manner. Excess metal precursor is removed from thereaction space by purging and/or evacuating the chamber (200).

Subsequently, a gas phase pulse of a second reactant is introduced intothe reaction space (300), where it reacts with the adsorbed metalprecursor in a self-limiting manner. The second reactant will beselected based on the nature of the metal containing film beingdeposited. For forming a metal containing film, the second reactant maystrip ligands from the adsorbed species. In the case of a compound filmthe second reactant may also contribute to the film, for example it maycontribute carbon (to form a metal carbide film) or nitrogen (to formmetal nitride film). Thus, the film may comprise a single metal speciesor, through the use of multiple reactants, a combination of species, forexample one or more metal species, nitrogen, carbon etc. . . . .

After sufficient time for it toreact with the adsorbed first reactant,the second reactant is removed from the reaction space (400). If a thinfilm of a desired thickness has been formed, the process may beterminated (500). However, if additional deposition is desired, thecycle may be begun again (600). As discussed below, subsequent cyclesmay or may not be identical to the previous cycle.

By alternating the provision of the metal precursor and the secondreactant, a metal containing thin film of the desired composition andthickness can be deposited. A growth rate of about from 0.1 to 1.5Å/cycle is typically achieved in ALD processes. Growth rates andsuitable growth temperatures depend, in part, upon the metal precursorchosen and can be readily determined by the skilled artisan.

Optionally, an inactive gas can be used as a carrier gas duringdeposition. Inactive gas may also be used to purge the reaction chamberof excess reactant and reaction by-products, if any, between reactantpulses.

The deposition can be carried out at normal pressure, but it ispreferred to operate the process at reduced pressure. Thus, the pressurein the reactor is typically from about 1 to about 100 mbar, preferablyfrom 5 to about 50 mbar.

The reaction temperature can be varied depending, in part, on theevaporation temperature and the decomposition temperature of theprecursor. In some embodiments, the range is from about 20° C. to about500° C., preferably from about 100° C. to about 400° C., more preferablyfrom about 200° C. to about 400° C. The substrate temperature ispreferably low enough to keep the bonds among thin film atoms intact andto prevent thermal decomposition of the gaseous reactants. On the otherhand, the substrate temperature is preferably high enough to keep thesource materials in gaseous phase and avoid condensation. Further, thetemperature is preferably sufficiently high to provide the activationenergy for the surface reaction.

The substrate can be of various types. Examples include, withoutlimitation, silicon, silica, coated silicon, germanium,silicon-germanium alloys, copper metal, noble metals group (includingsilver, gold, platinum, palladium, rhodium, iridium and ruthenium),nitrides, such as transition nitrides, e.g. tantalum nitride TaN,carbides, such as transition carbides, e.g. tungsten carbide WC, andnitride carbides, e.g. tungsten nitride carbide WN_(x)C_(y). Thepreceding thin film layer deposited on the substrate, if any, will formthe substrate surface for the next thin film.

Formation of a Elemental Metal Thin Film

According to some embodiments, a metal containing cyclopentadienylcompound as described above, preferably one wherein the metal is notdirectly bonded to a halide or oxygen atom, is used to produce anelemental metal thin film. The metal precursor may be selected fromcompounds according to Formulae I-VI as described above. In someembodiments, the elemental metal thin film is deposited by alternatelyand sequentially contacting the substrate with the metal containingcyclopentadienyl compound and a second reactant to deposit an elementalmetal thin film. In some embodiments, the second reactant is hydrogen orhydrogen plasma. In some particular embodiments, the metal precursor isa titanium cyclopentadienyl compound.

Formation of a Metal Nitride Thin Film

According to the preferred embodiments, a metal containingcyclopentadienyl precursor as described above, preferably wherein themetal is not directly bonded to a halide or oxygen atom, can be used toproduce a metal nitride thin film. The metal precursor may be selectedfrom compounds according to Formulae I-VI as described above. The metalcontaining cyclopentadienyl reactant is provided to the reaction spacealternately and sequentially with a nitrogen source material. In somesuch embodiments the nitrogen source material may be selected from thegroup consisting of NH₃, N₂ plasma, N₂/H₂ plasma, hydrazine, and/orhydrazine derivatives. In some particular embodiments a titanium nitridethin film is deposited.

Formation of a Metal Carbide Thin Film

A metal containing cyclopentadienyl precursor as provided above,preferably wherein the metal is not directly bonded to a halide oroxygen atom, can also be used in conjunction with a carbon compound toproduce a metal carbide thin film. Preferably the metal precursor isselected from compounds according to Formulae I-VI as described aboveand is provided alternately and sequentially with a secondcarbon-contributing reactant in an ALD process. In some embodiments, thecarbon compound is a hydrocarbon. In some such embodiments thehydrocarbon is selected from alkanes, alkenes, and alkynes.Additionally, in some embodiments, the carbon containing compound is onewith a central atom selected from group B, Al, Ga, In, Si, Ge, Sn, P,As, or S. In some particular embodiments, the metal containing precursoris a titanium cyclopentadienyl compound and the metal carbide thin filmis a titanium carbide thin film.

Formation of a Multicomponent Thin Film

In order to produce multicomponent thin films, at least one additionalmetal source material can be introduced to the ALD process. In somepreferred embodiments, each additional metal source material is providedin a separate pulse, with each cycle comprising feeding a vapor phasepulse of an additional metal source material, removing excess additionalmetal source material, providing a vapor phase pulse of a reactant, andremoving excess reactant. The same said reactant may be provided aftereach of the two or more different metal source material, or differentreactants (e.g., reducing agents, carbon sources, and/or nitrogensources) may be used to react with different metal precursors. Thenumber of cycles for each metal precursor may be equivalent or may bedifferent, depending on the composition of the film that is desired.

In other embodiments, a multicomponent thin film is deposited by ALDprocesses with at least two growth sub-cycles comprising a firstsub-cycle involving feeding a vapor phase pulse of a first metalcontaining precursor, removing excess first metal containing precursor,providing a vapor phase pulse of a first reactant, removing excess firstreactant; then a second sub-cycle involving feeding a vapor phase pulseof a second metal containing precursor, removing excess second metalcontaining precursor, providing a vapor phase pulse of a secondreactant, and then removing excess second reactant. In some embodiments,a third, fourth, fifth etc. . . . metal compound is used, typically inadditional sub-cycles. The ratio of subcycles can be selected dependingon the desired thin film composition. At least one sub-cycle deposits adifferent material from another sub-cycle. A metal containingcyclopentadienyl precursor as described above is used a the metalcontaining precursor in at least one subcycle.

In some embodiments, ALD processes for producing a multicomponent thinfilm comprise at least one elemental metal sub-cycle. The processespreferably comprise contacting a substrate with alternate and sequentialvapor phase pulses of a metal precursor and a reactant. The firstreactant may be selected from hydrogen or hydrogen plasma. The metalprecursor is preferably a metal containing cyclopentadienyl compound asdescribed above. The metal containing cyclopentadienyl may be, forexample, selected from the compounds having Formulae I-VI as described.

In other embodiments, ALD processes for producing a multicomponent thinfilm comprise at least one metal nitride sub-cycle. The processespreferably comprise contacting a substrate with alternate and sequentialvapor phase pulses of a metal precursor and a reactant. In someembodiments the metal precursor is preferably a metal containingcyclopentadienyl compound as described above. In some embodiments thenitrogen containing material is selected from the group consisting ofNH₃, N₂ plasma, N₂/H₂ plasma, hydrazine, and/or hydrazine derivatives.In some embodiments, the metal containing cyclopentadienyl may beselected from the compounds having Formulae I-VI as described.

In another embodiment, multicomponent thin film deposition processescomprising at least one metal carbide sub-cycle are conducted by atomiclayer deposition type processes. Thse sub-cycles preferably comprisecontacting a substrate with alternate and sequential vapor phase pulsesof a metal precursor and a carbon source material, where the metalprecursor is preferably a metal containing cyclopentadienyl compound asdescribed above. In some embodiments, the carbon source material is ahydrocarbon, preferably a hydrocarbon selected from alkanes, alkenes,and alkynes. Additionally, in further embodiments, the carbon containingcompound is one with a central atom selected from group B, Al, Ga, In,Si, Ge, Sn, P, As, or S. Additionally, the metal containingcyclopentadienyl may be selected from the compounds having Formulae I-VIas described.

In other embodiments, a pulse of an additional metal precursor is thesecond source material provided after the first metal precursor in thesame deposition cycle. A first reactant is then provided to convert thetwo metals into the desired type of thin film. Additional metalprecursors may also be provided prior to provision of a reactant. Inother embodiments, a reactant is provided after each metal sourceprecursor, as discussed above.

In addition, in some embodiments, the additional metal compound isprovided in each ALD cycle. That is, a pulse of the second metalcompound is provided for each pulse of the first metal precursor.However, in other embodiments, the second metal compound is providedintermittently in a selected ratio to the first metal precursor pulsesin the deposition process. Preferably, at least one of the metalprecursors, for the disclosed ALD processes, is a metal containingcyclopentadienyl compound as described above, such as a titaniumcyclopentadienyl compound.

Although referred to as the “first” reactant or metal precursor, the“second,” and “third” etc., these labels are for convenience and do notindicate the actual order of the metal source materials or reactants.Thus, the initial ALD cycle may be started with any of the phasesdescribed above. However, one of skill in the art will recognize that ifthe initial ALD cycle does not begin with the metal source phase, atleast two ALD cycles will typically need to be completed to begindeposition of the desired thin film. As is well-known in the art,typically less than a monolayer of a material is deposited in each ALDcycle due, in part, to steric hindrance and the availability of reactivesites on the substrate surface.

At least one of the additional metal precursors can be metal compoundscomprising a single metal or complex metal compounds comprising two ormore metals. In some embodiments, the metal compounds comprise at leastone metal selected from the group consisting of Al, Ga, In, Sc, Ti, V,Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Tc, Ru, Rh, La, Hf, Ta, W, Re, Os,and Ir. In other embodiments at least one metal is a trivalent metal.

Since the properties of the metal compounds vary, the suitability ofeach metal compound for use in the ALD processes disclosed herein has tobe considered. The properties of the compounds can be found, e.g., in N.N. Greenwood and A. Earnshaw, Chemistry of the Elements, 1^(st) edition,Pergamon Press, 1986. The suitability of any particular compound canreadily be determined by a skilled artisan.

The novel thin film deposition processes will find extensive applicationas semiconductors, insulators and ferroelectrics. For example, the filmsformed according to preferred methods may define, e.g., diffusionbarriers in integrated circuits, metal gates in transistors, or metalelectrodes in capacitor structures. In some embodiments, metal nitridefilms may serve as top/bottom electrodes for MIM/MIS capacitors, such aseDRAM, DRAM, RF decoupling, and planar and 3-D capacitors.

In other embodiments, metal carbide films can be formed as a componentof an integrated circuit, such as, e.g., a conductive diffusion barrierforming a part of a line in a dual damascene structure, a metal gateelectrode, such as an NMOS gate electrode, or an anti-reflectivecoating. In other embodiments, the metal carbide film may form a part ofhard coating on a substrate to protect against mechanical wear, or maybe used as a component of a corrosion protection layer. In still otherembodiments, the metal carbide film can be, e.g., used as part of achemical reaction catalyst or as an etch stop barrier.

The metal containing cyclopentadienyl precursors described herein foruse in ALD processes not only lack many of the problems associated withthermal instability, but also provides for better film uniformity byavoiding oxygen and halide contamination.

Although the foregoing invention has been described in terms of certainpreferred embodiments, other embodiments will be apparent to those ofordinary skill in the art. Additionally, other combinations, omissions,substitutions and modification will be apparent to the skilled artisan,in view of the disclosure herein. Accordingly, the present invention isnot intended to be limited by the recitation of the preferredembodiments, but is instead to be defined by reference to the appendedclaims.

What is claimed is:
 1. An atomic layer deposition process for depositinga metal containing thin film on a substrate in a reaction spacecomprising one or more deposition cycles comprising: contacting thesubstrate with a pulse of a vapor phase first reactant comprising avolatile zirconium compound having the formula (R¹R²R³R⁴R⁵Cp)_(x)-ZrR⁰_(z)—(NR¹R²)_(y); contacting the substrate with a pulse of a vapor phasesecond reactant; and wherein in the first reactant each of the R¹groups, each of the R² groups, and each of the R³, R⁴, R⁵, and R⁰ groupsis independently selected from hydrogen, and linear and branched C₁-C₂₀alkyl, alkenyl and alkynyl groups which are independently substituted orunsubstituted, and wherein x≧1, y≧1 and z≧0.
 2. The process of claim 1,wherein an inert gas serves as a carrier gas for the first reactant. 3.The process of claim 1, wherein the atomic layer deposition processcomprises a plasma enhanced atomic layer deposition process.
 4. Theprocess of claim 1, wherein the one or more deposition cycles comprisepurging the reaction space between the pulses of the first and secondreactants.
 5. The process of claim 1, wherein each of the R¹ groups andeach of the R² groups is independently selected from linear and branchedC₁-C₄ alkyl, alkenyl, and alkynyl groups, which are independentlysubstituted or unsubstituted.
 6. The process of claim 5, wherein each ofthe R¹ groups and each of the R² groups is independently selected fromlinear and branched C₁-C₄ alkyl groups which are independentlysubstituted or unsubstituted.
 7. The process of claim 6, wherein each ofthe R¹ groups and each of the R² groups is independently selected frommethyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl.
 8. Theprocess of claim 1, wherein z is
 0. 9. The process of claim 8, wherein yis
 3. 10. The process of claim 1, wherein the zirconium compoundcomprises a modified cyclopentadienyl group.
 11. The process of claim10, wherein the modified cyclopentadienyl group is selected from thegroup consisting of Me₅Cp, MeCp, EtCp, and Me₃SiCp.
 12. The process ofclaim 1, wherein the temperature is 200° C. to 400° C.
 13. The processof claim 1, wherein the second reactant contributes nitrogen to themetal containing thin film.
 14. The process of claim 1, wherein thesecond reactant contributes carbon to the metal containing thin film.15. The process of claim 1, wherein the second reactant contributesoxygen to the metal containing thin film.
 16. The process of claim 1,wherein the metal containing thin film is an insulating thin film.
 17. Aplasma enhanced atomic layer deposition process for producing amulticomponent metal containing thin film on a substrate comprising: afirst deposition cycle comprising alternately and sequentiallycontacting the substrate with a first metal precursor comprising avolatile cyclopentadienyl compound and a first reactant comprising N, Cor O, wherein the first metal precursor has the formula(R¹R²R³R⁴R⁵Cp)_(x)-MR⁰ _(z)—(NR¹R²)_(y) wherein: M is zirconium; each ofthe R¹ groups, each of the R² groups, and each of the R³, R⁴, R⁵, and R⁰groups is independently selected from hydrogen and linear and branchedC₁-C₂₀ alkyl, alkenyl and alkynyl groups which are independentlysubstituted or unsubstituted, and x≧1, y≧2 land z≧0.
 18. The process ofclaim 17, wherein the first reactant is a plasma reactant.
 19. Theprocess of claim 17, wherein the first reactant contributes oxygen tothe multicomponent metal containing thin film.
 20. The process of claim17 additionally comprising a second deposition cycle comprisingcontacting the substrate with a second metal precursor and a secondreactant.
 21. The process of claim 20, wherein the second metalprecursor is different from the first metal precursor.
 22. The processof claim 20, wherein the second reactant is different from the firstreactant.
 23. The process of claim 22, wherein the second reactantcontributes a different species to the multicomponent thin film from thefirst reactant.